Ultrasound-induced cavitation of air microbubbles to clean biofilm off of teeth surfaces, as well as below the gum line, is generally known. An example of such ultrasonic technology is shown in U.S. Pat. No. 5,138,733 to Bock. Other examples include U.S. Pat. No. 3,809,977 to Balamuth and U.S. Pat. No. 7,269,873 to Brewer et al. Further, there have been commercial dental appliances which utilize an ultrasound/microbubble approach to cleaning teeth. Such appliances, however, typically have one or more significant disadvantages.
First, while the cleaning action produced by cavitation of the microbubbles generally can be strong in the vicinity of some of the bubbles, not all of the bubbles are strongly active, and even the ones which are active tend to remain in a single position longer than necessary to clean an area around that position. Overall cleaning action is thus believed to be weaker than otherwise could be the case with the typical number of bubbles available and with the same ultrasound excitation.
Further, cleaning is spotty on a macroscopic level. Certain regions on the surfaces of the teeth will exhibit strong cleaning, while others exhibit almost no cleaning at all. This is possibly due to variations in ultrasound intensity caused by interference effects due to reflection of the ultrasound off the various teeth surfaces.
Still further, adequate bubble concentration is difficult to maintain in the teeth recesses where the cavitation could actually have the most beneficial effect, because of ineffective cleaning by scrubbing. This lack of bubble concentration is likely due to the destruction of bubbles by the same ultrasound which would ordinarily produce cleaning.
Accordingly, an ultrasound/microbubble system is desired to either complement existing manual or power toothbrushes or mouthpieces, or to be used alone in order to produce a significant cleaning effect on the teeth, along the gum line and in the interproximal areas of the teeth.